查找使用阿拉丁产品的科研文献

Ultra-sensitive flexible accelerometer based on PVDF for self-powered wireless sensing system

Bozhi Wu,Ke Li,Lei Wang,Yongqiang Yang,Kuibo Yin,Meng Nie,Litao Sun

Flexible accelerometers (AC) are widely applied in fields such as sensor networks, motion monitoring, and wearable electronics. However, developing self-powered flexible accelerometers with enhanced sensitivity remains a challenge. Herein, a self-powered flexible accelerometer based on electrospun ZnO@PVDF (ZP) is proposed. ZnO provides nucleation sites for the β-phase in PVDF, increasing its crystallization and piezoelectricity. Meanwhile, the piezoelectric performance of the device is further enhanced due to the piezoelectric synergy effect between ZnO and PVDF. ZP-AC has a sensitivity of up to 4.558   V/g (12.2 times higher than pure PVDF-AC), which is an order of magnitude improved compared to the reported other AC based on piezoelectric mechanism. Moreover, the proposed ZP-AC shows superb durability (12,000 cycles). A wireless acceleration sensing system based on ZP-AC is designed through acquisition circuitry and successfully applied to monitor the acceleration of automobile collisions, bicycle wheel rotation, simulated punches, and badminton swings. This study provides significant support for the design and performance optimization of self-powered flexible accelerometers and promotes their widespread application in the field of sensing and monitoring.

Hydrophilic modification of PVDF microfiltration membranes by adsorption of facial amphiphile cholic acid

Meng-Xin Hu,Ji-Nian Li,Shi-Lin Zhang,Liang Li,Zhi-Kang Xu

Amphiphilic molecules have been widely used in surface modification of polymeric materials. Bile acids are natural biological compounds and possess special facial amphiphilic structure with a unusual distribution of hydrophobic and hydrophilic regions. Based on the facial amphiphilicity, cholic acid (CA), one of the bile acids, was utilized for the hydrophilic modification of poly(vinylidene fluoride) (PVDF) microfiltration membranes via the hydrophobic interactions between the hydrophobic face of CA and the membrane surfaces. Ethanol, methanol, and water were respectively used as solvent during CA adsorption procedure. Their polarity affects the CA adsorption amount, as similar to CA concentration and adsorption time. There are no changes on the membrane surface morphology after CA adsorption. The hydrophilicity of PVDF membranes is greatly enhanced and the water drops permeates into the CA modified membranes quickly after modification. All these factors benefit to the permeation flux of membrane for water. When CA concentration is higher than 0.088   M, the water permeation flux is doubled as compared with the nascent PVDF membrane and shows a good stability during filtration procedure. These results reveal the promising potential of facial amphiphilic bile acids for the surface modification of polymeric materials.

Enhanced performance of forward osmosis membranes by incorporating PVDF substrates with hydrophilic nanofillers

Hui-Min Cui,Xi Yan,Yan Chen,Wen-Yan Xu,Wan-Zhong Lang

Hydrophilic attapulgite (AT) and functional oxidized multi-walled carbon nanotubes (O-MWCNTs) are introduced to the polyvinylidene fluoride (PVDF) substrates to prepare improved performance of thin-film composite (TFC) membranes for forward osmosis (FO) process. The improved hydrophilicity of substrates can make for forming free-defect polyamide (PA) layer and enhance the permeability performance of the as-prepared TFC membranes. The effects of the single or composite addition of two nanofillers on the hydrophilicity, membrane morphology, porosity and mechanical strength of as-prepared substrates are investigated in detail. The results show that hydrophilic, porous and high-flux substrates are prepared and the corresponding TFC membranes own improved water flux and better selectivity. In a word, the PVDF/AT/O-MWCNTs TFC membrane receives a better water flux (Jv) of 28.23 and 20.37 L.m–2.h–1 and a lower reverse salt flux (Js) of 9.5 and 6.5 g.m-2.h-1 in pressure-retarded osmosis (PRO) mode (active layer facing draw solution, AL-DS) and FO mode (active layer facing feed solution, AL-FS). The draw solution and feed solution are 2M NaCl aqueous solution and deionized (DI) water, respectively. This study develops a brand-new way for preparing substrate for FO process.

G-CNTs/PVDF mixed matrix membranes with improved antifouling properties and filtration performance

Guo Xiaoyan,Li Chunyu,Li Chenghao,Wei Tingting,Tong Lin,Shao Huaiqi,Zhou Qixing,Wang Lan,Liao Yuan

Although carbon nanomaterials have been widely used as effective nanofillers for fabrication of mixed matrix membranes (MMMs) with outstanding performances, the reproducibility of the fabricated MMMs is still hindered by the non-homogenous dispersion of these carbon nanofillers in membrane substrate. Herein, we report an effective way to improve the compatibility of carbon-based nanomaterials with membrane matrixes. By chemically conjugating the oxidized CNTs (o-CNTs) and GO using hexanediamine as cross-linker, a novel carbon nanohybrid material (G-CNTs) was synthesized, which inherited both the advanced properties of multi-walled carbon nanotubes (CNTs) and graphene oxide (GO). The G-CNTs incorporated polyvinylidene fluoride (PVDF) MMMs (GCNTs/PVDF) were fabricated via a non-solvent induced phase separation (NIPS) method. The filtration and antifouling performances of G-CNTs/PVDF were evaluated using distillate water and a 1 g/L bovine serum albumin (BSA) aqueous solution under 0.10 MPa. Compared to the MMMs prepared with o-CNTs, GO, the physical mixture of o-CNTs and GO and pure PVDF membrane, the G-CNTs/PVDF membrane exhibited the highest water flux up to 220 L/m 2 /h and a flux recovery ratio as high as 90%, as well as the best BSA rejection rate. The excellent performances should be attributed to the increased membrane pore size, porosity and hydrophilicity of the resulted membrane. The successful synthesis of the novel nanohybrid G-CNTs provides a new type of nanofillers for MMMs fabrication.

Effect of modified attapulgite addition on the performance of a PVDF ultrafiltration membrane

Yalei Zhang,Jing Zhao,Huaqiang Chu,Xuefei Zhou,Yong Wei

Attapulgite (APT), which is a highly hydrophilic fibrillar mineral in nature, is a promising new additive for preparation of ultrafiltration (UF) membranes. In this work, APT particles were first grafted with NH 2 using the silane coupling agent APTES to detach the crystal bundles to single crystal and enhance the uniform dispersion in an organic polymer matrix ; these components were subsequently incorporated into a polyvinylidene fluoride (PVDF) matrix to develop a hybrid membrane via a phase inversion method. The modified APT mineral was characterized using SEM and FTIR to confirm the presence of the amine group on the surface. Other techniques (i.e., FTIR-ATR, XRD and TGA) and parameters (i.e., porosity, the average pore size , contact angle and filtration measurements of water and bovine serum albumin (BSA)) were applied and measured to study the performance of the UF membranes. Compared with the pure PVDF sample, the APT particle blended membranes exhibited better thermal stability, smaller pore size and higher hydrophilicity. More importantly, the values for pure flux, flux recovery ratio (FRR) and rejection of BSA solution all indicated that the PVDF/APT hybrid membranes offer excellent hydrophilicity, water permeability and good antifouling performance.

Construction of Superhydrophobic Surfaces Enhanced by Silanized-CNC-Assisted PVDF/PDMS Microsphere Coating

Coatings based on polyvinylidene fluoride (PVDF) and poly(dimethylsiloxane) (PDMS)-based polymeric microspheres can be easily fabricated via non-solvent-induced phase separation (NIPS) and electrostatic spraying (ES) techniques. Both techniques are promising strategies for constructing superhydrophobic surfaces on various substrates. However, PVDF and PDMS inherently suffer from severe aggregation, which generates oversized particles and inhomogeneous microstructures. Conventionally, costly and environmentally hazardous dispersants are required to alleviate this issue, severely restricting the industrial scalability and practical application of such coatings. In this work, methyltrimethoxysilane-modified cellulose nanocrystals (Si-CNCs) were introduced as a green multifunctional modifier to tackle these issues. The results revealed that as structural building blocks and dispersants, Si-CNCs inhibited polymer aggregation via electrostatic repulsion and steric hindrance, refined the particle size and formed uniform micro/nano hierarchical structures. Increasing Si-CNC loading further improved polymer dispersion and superhydrophobic performance. Coatings fabricated by ES showed better hydrophobicity than those fabricated by NIPS. ES achieved a water contact angle (WCA) of 160–166° and a sliding angle (SA) near 1° on cotton fabric, while NIPS had a WCA of 153.8–158° and an SA of around 2°. Wood and glass substrates also obtained favorable superhydrophobicity, with WCAs above 150° and SAs below 1°. Furthermore, all modified surfaces exhibited excellent abrasion resistance. This work provides a relatively eco-friendly, environmentally sustainable, scalable and substrate-flexible strategy for fabricating high-performance PVDF/PDMS-based superhydrophobic coatings.

An rGO/cellulose acetate/PVDF piezoelectric separator for mitigating self-discharge in supercapacitor

Kewei Shu,Wenjuan Li,Yi Zhang,Yan Zong,Huilan Li,Yu Wang,Zixiong Sun

Flexible, miniature, and lightweight supercapacitor is ideal power source for next-generation portable and wearable electronics. However, their widespread application is limited by a critical drawback, self-discharge, which leads to energy loss during idle periods. To this end, a polyvinylidene fluoride (PVDF)-based nanofiber separator with piezoelectric properties that can effectively suppress self-discharge in supercapacitors, was prepared via electrospinning. By incorporating hydrophilic cellulose acetate (CA) and reduced graphene oxide (rGO) into the PVDF matrix, both the electrolyte affinity and piezoelectric output of the separator are significantly enhanced. The resulting rGO/CA/PVDF composite membrane exhibits outstanding mechanical flexibility, high porosity, excellent electrolyte uptake, making it highly suitable separator for flexible supercapacitor. Supercapacitors equipped with such separator exhibit superior electrochemical performance with a specific capacitance of 178.2 F/g at 10 A/g. Notably, an impressive capacitance retention of 79 % was achieved after 24 h of self-discharge test. The reduction in self-discharge is primarily due to the limited diffusion of electrolyte ions, induced by the polarized rGO/CA/PVDF composite separator endowed with improved piezoelectric characteristics. This work highlights the potential of piezoelectric separators as an effective strategy for long-term energy retention, and offers new insights into the rational design of functional separators with self-discharge mitigation capabilities.

ZIF-8/CS/PVDF Composite membranes: dye separation and self-cleaning properties exploration

Sui Xingyu,Hu Zhengwen,Peng Lin,Shu Yong,Jiang Luming,Zhao Guixiang

With the rapid progress of urbanization and industrialization, water pollution has become an increasingly serious issue, particularly due to dye wastewater, which contains numerous harmful substances and is difficult to treat effectively. Dye wastewater contains many harmful substances and is difficult to treat effectively. Traditional treatment methods are often inefficient and economically unsustainable. In contrast, membrane separation technology offers high separation efficiency and environmental benefits, making it a promising approach for water purification. Therefore, in this paper, the hydrophilic modification of PVDF membranes was carried out by adding ZIF-8 and chitosan(CS), and at the same time, the membranes were endowed with the ability of light self-cleaning. ZIF-8, a metal–organic framework (MOF) material, was synthesized using water as the solvent through the reaction of zinc nitrate with 2-methylimidazole. The PVDF membranes were modified by physical co-mingling, and ZIF-8/CS/PVDF composite membranes with different contents of ZIF-8 and CS were prepared by the submerged precipitation phase transition method. The performance test results demonstrated that the composite membranes doped with ZIF-8 and CS exhibited significant improvements in water contact angle, pure water flux, and dye wastewater treatment performance. Notably, the modified membranes showed exceptional dye removal efficiency and enhanced resistance to membrane fouling. Furthermore, the results of photocatalytic self-cleaning experiments revealed that the modified membranes effectively degraded Congo red and methylene blue dyes under Xenon lamp irradiation, highlighting their excellent photocatalytic self-cleaning capability. These findings suggest that the ZIF-8/CS/PVDF-modified membrane holds great potential for water treatment and self-cleaning applications, achieving up to 93.06% dye rejection and a pure water flux of 95.89 L m −2  h −1 , more than double that of the pristine PVDF membrane.

Microsphere-Fiber Interpenetrated Superhydrophobic PVDF Microporous Membranes with Improved Waterproof and Breathable Performance

Gaoshuo Jiang,Liqiang Luo,Lu Tan,Jinliang Wang,Shenxiang Zhang,Feng Zhang,Jian Jin

Superhydrophobic membranes with extreme liquid water repellency property are good candidates for waterproof and breathable application. Different from the mostly used strategies through either mixing or postmodifying base membranes with perfluorinated compounds, we report in this work a facile methodology to fabricate superhydrophobic microporous membranes made up of pure poly(vinylidene fluoride) (PVDF) via a high-humidity induced electrospinning process. The superhydrophobic property of the PVDF microporous membrane is contributed by its special microsphere-fiber interpenetrated rough structure. The effective pore size and porosity of the PVDF membranes could be well tuned by simply adjusting the PVDF concentrations in polymer solutions. The membrane with optimized superhydrophobicity and porous structure exhibits improved waterproof and breathable performance with hydrostatic pressure up to 62 kPa, water vapor transmission rate (WVT rate) of 10.6 kg m–2 d–1, and simultaneously outstanding windproof performance with air permeability up to 1.3 mm s–1. Our work represents a rather simple and perfluorinated-free strategy for fabricating superhydrophobic microporous membranes, which matches well with the environmentally friendly requirement from the viewpoint of practical application.

Gradient CNT/PVDF piezoelectric composite with enhanced force-electric coupling for soccer training

Zeng Wanghong,Deng Weili,Yang Tao,Wang Shenglong,Sun Yue,Zhang Jieling,Ren Xiarong,Jin Long,Tang Lihua,Yang Weiqing

Real-time monitoring of ball–shoe interactions can provide essential information for high-quality instruction in personalized soccer training, yet existing monitoring systems struggle to reflect specific forces, loci, and durations of action. Here, we design a self-powered piezoelectric sensor constructed by the gradient carbon nanotube/polyvinylidene fluoride (CNT/PVDF) composite to monitor the interactions between the ball and the shoe. Two-dimensional Raman mapping demonstrates the gradient structure of CNT/PVDF prepared by programmable electrospinning combined with a hot pressing. Benefitting from the synergistic effect of local polarization caused by the enrichment of CNT and the reduced diffusion of silver patterns in gradient structure, the as-prepared composite exhibits enhanced force-electric coupling with an excellent sensitivity of 80 mV/N and durability over 15,000 cycles. On this basis, we conformally attach a 3 × 3 sensor array to a soccer shoe, enabling real-time acquisition of kick position and contact force, which could provide quantitative assessment and personalize guidance for the training of soccer players. This self-powered piezoelectric sensor network system offers a promising paradigm for wearable monitoring under strong impact forces.

Preparation of Si@PVDF composite microspheres by electrostatic spraying for enhanced energetic characteristics

Huiqing Mao,Xiandie Zhang,Rui Cui,Chun Zhang,Xiang Zhou

In this study, Si@PVDF composite microspheres are prepared by the electrostatic spraying method. The spheres are with average diameter of around 2 μm (when at ideal stoichiometry), within which Si nanopowder is uniformly distributed. The exothermic properties of samples are studied through simultaneous thermogravimetry and differential scanning calorimetry . Benefiting from the improved interfacial contact quality, Si@PVDF shows increased chemical reactivity in terms of reduced reaction onset temperature , peak temperature and apparent activation energy than those of physically mixed Si/PVDF counterpart. Si/PVDF cannot be ignited through Joule heating , either in the powder of pellet form, while self-sustained combustion propagation is observed for Si@PVDF pellets. The combustion behaviors of Si@PVDF pellets are systematically studied in open-air (where light signal is analyzed) and constant-volume (where pressure signal is analyzed) conditions. The results show that the combustion process is influenced by the equivalence ratio, porosity of the pellet and the accessibility of O 2 gas in the environment. Overall, the encapsulation of Si nanopowder into PVDF microspheres using electrostatic spraying shortens the mass and heat transfer distance and thus realizes enhanced energetic characteristics.

PDMS/PVDF Electrospinning Membranes for Water-in-Oil Emulsion Separation and UV Protection

Jie Li,Yushan Li,Yiyi Lu,Wentian Shi,Huafeng Tian

With industry development, the separation of oily wastewater is becoming more critical. Inspired by organisms such as lotus leaves, biomimetic superhydrophobic surfaces with micro-nano structures have shown great potential in this regard. In this work, PDMS/PVDF oil–water separation membranes with designed microstructures were prepared by electrospinning technology. The membrane-forming effect of electrospinning with different ratios of PDMS and PVDF was studied. The study found that membranes with high PDMS content were more likely to form microspheres, and PDMS tended to concentrate on the microspheres. The results also showed that the microspheres would bring better hydrophobicity to the membrane. When the ratio of PDMS to PVDF is 1:2, the membrane has a water contact angle of up to 150° and an oil contact angle of 0°. At this ratio, the separation efficiency of the membrane for the water-in-oil emulsion is 98.7%, and it can still maintain more than 98% after ten separation cycles, which is a good candidate for oil–water separation. Furthermore, microspheres enable the membrane to achieve macroscopic uniformity and microscopic phase separation so that the membranes have both good elongation and fracture strength. In addition, the PDMS/PVDF membranes also exhibit excellent UV resistance, and their UV protection factor is greater than 185, making them a potential UV protective material.Keywords:electrospinning;polydimethylsiloxane;polyvinylidene difluoride;oil–water separation;UV protection